The minister suggested the Sutherland shire is right behind the government, based on feedback he’s received in the Cronulla mall, at the beach and at Miranda Fair.

Refugee lawyers and human rights advocates might be pressing for an overhaul of the regime, but locals in the shire had given Morrison anything but the cold shoulder, encouraging him to “keep giving it to ’em and don’t back down”, he said.

Journalist Murray Trembath also noted Morrison was also “surprisingly upbeat” when asked about speculation he could one day become prime minister.

“I am up for any challenge, but right now I know what the challenge is and the challenge is this job,” Morrison told the paper.

Morrison said he found speculation about his leadership potential “encouraging and flattering” – but said he was not inclined to dwell on it.

The minister said he takes the advice he once received from John Howard: do your current job well and the rest will take care of itself. Morrison is regarded by his parliamentary colleagues in Canberra as highly ambitious.

In the interview the minister shrugged off criticism the border protection regime was amoral. He noted he was “not an insecure person” and believed in what he was doing.

Based on the remarks attributed to him in the interview, Morrison believes criticism of his management of the border protection portfolio, or the Operation Sovereign Borders policy more generally, is simply a “campaign” by advocates who want softer immigration policies.

He saw the criticism as personally motivated, he added, which worked as encouragement for him to stand his ground.

Asked about the comments on leadership, cabinet colleague and attorney-general George Brandis said in Sydney on Friday that Morrison was a “tremendously successful minister”.

Brandis said he not seen the report, but Morrison was one of the “stars” of the government.